A technique was developed which increases the occurrence of monopolar and multipolar divisions, in the primary cultures of lung epithelium of Taricha granulosa. Time lapse technique (various types of microscopes) was correlated precisely (20 secs.) with EM and immunochemical studies visualizing microtubules in the light microscope. Basic findings are: (1) In monopolar division only primal (to the diplosome) kinetochore has kinetochore fibre. Sister distal kinetochore is immersed in tubulin pool and competent to establish kinetochore fibre. This occurs only when the second aster penetrates the monopolar spindle from behind. These data question the assumed role of the kinetochore as the microtubule nucleating site in the living cells. (2) During early prometaphase all chromosomes of the set (2n equals 22) may exhibit persistent monopolar orientation toward two opposite poles. Such monopolar half-spindles may move apart in anaphase-like fashion up to 200 micrometers without any detectable "interzonal" microtubular system. The prometaphase spindle is torn apart into two autonomously moving half-spindles. This observation is incompatible with any interpretation assuming active interzone sliding and proves one of the basic assumptions of the zipper hypothesis. The molecular mechanism of chromosome movements remains unknown. UV microbeam and cytochemical studies are planned. It is hoped that rare "special cases" (about 20 observed so far) can be repeated routinely in experimental conditions.